Generally, an injection molding apparatus is comprised of a bed and a mold clamping mechanism placed on the bed. Mold clamping is performed by the mold clamping mechanism. A resin material is injected into a mold from an injection machine to thereby provide a molded article. Mold clamping mechanisms employing various devices are known (see, e.g., Japanese Utility Model Registration No. 2587035, hereinafter referred to as Patent Literature 1).
The mold clamping mechanism disclosed in Patent Literature 1 will be described below with reference to FIG. 10 hereof.
As shown in FIG. 10, the mold clamping mechanism 100 wherein a fixed platen 102 and a pressure receiving platen 103 are secured to a bed 101, tie-bars 104, 104 are disposed to extend between the two platens, a movable platen 105 is mounted to the tie-bars 104, 104, and the movable platen 105 is moved by means of a mold clamping cylinder 106 provided to the pressure receiving platen 103.
The mold clamping mechanism disclosed in the registration is featured in the fixed platen 102 having a cutout 107. In Patent Literature 1, the fixed platen 102 is described as receiving a reaction force and elastically deforming, as shown by a phantom line A, upon mold clamping. However, the present inventors have perceived a contradiction present in the description.
Such a contradiction will be described with reference to FIG. 11 hereof. The fixed platen 102 is firmly secured to the bed 101 by a leg part 108. A vicinity of the leg part 108 has higher rigidity than other parts. As a result, a part shown by a phantom line B deforms only slightly while a part shown by a phantom line C and being remote from the let part 108 deforms largely. A maximum deformation point 109 resides at the center of the phantom line C and is deviated upward from the center of a nozzle 111 of an injection machine. As a result, attachment of the nozzle 111 of the injection machine to the mold becomes unstable whereby disadvantages such as an occurrence of resin leakage, failure in uniform transmission of a mold clamping force, mold deformation and production of defective products are experienced.
For achieving appropriate or stable attachment of the nozzle 111, uniform deformation as shown by a phantom line A is required. However, the leg part should not be omitted.
Consequently, there is a demand for an improvement in the construction of the fixed platen such that while having the leg part connected to the bed, the fixed platen exhibits uniform deformation and does not impart adverse effects of the deformation to the mold and resulting products.